Nowadays, with the rapid development of high-speed transmission technologies, increasingly higher requirements are imposed on the design of high-frequency signal transmission lines. A conventional high-frequency signal transmission line generally adopts a coaxial cable. When a large number of signals need to be transmitted, many coaxial cables need to be bundled together. However, in a device with limited wiring space, the cables often need to be bent. In this case, the coaxial cables that are bundled together do not have desirable flexibility, making it inconvenient for line installation. In addition, when a cable is used to connect two signal transmission modules, wires at two ends of the cable must be soldered to corresponding contacts. However, since the coaxial cables are bundled together and manual cabling is required, automated production cannot be achieved, resulting in a low production efficiency.
For the above reasons, it has been proposed in the related art to replace the coaxial cables with a flexible printed circuit board so as to solve the above problems. However, provided that the wiring area is constant, when the number of signal lines is increased, in order to achieve an anti-electromagnetic interference effect close to that of the coaxial cables, more than three wiring layers need to be disposed on the flexible printed circuit board and high-frequency lines of different layers need to be staggered, so that high-frequency transmission lines of different layers do not interfere with each other. It is known to those skilled in the art that the larger the number of wiring layers in a circuit board is, the more complex the manufacturing process is, and the higher the cost will be.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.